I noticed a big enough difference across the cores when I delidded my 3570k, but not that much of a difference when changing from this liquid metal to that of the GC Extreme paste.
I wish that I had just scraped off the black sealant around the CPU and IHS as I expect that it had a big impact of the closeness of the IHS to the core and thus compromise the cooling rather than it just being the TIM used.
When I passed the 3570k back to my Son I applied a thin and even layer of black sealant to reattach the IHS and the temps increased to the point where I simply removed the lid and the black stuff and the temps went back down to something more reasonable.
I prefer to use the GC Extreme, once warmed up a bit, as the corrosive and conductive properties of this liquid metal are made far worse if it gets into places where it shouldn't...! Cleaning it off is a challenge as well...!